U.S. patent number 10,131,036 [Application Number 14/492,543] was granted by the patent office on 2018-11-20 for method and device for manufacturing elastic abrasive method for blasting the elastic abrasive including method for recycling the elastic abrasive and device for blasting the elastic abrasive including device for recycling the elastic abrasive.
This patent grant is currently assigned to FUJI MANUFACTURING CO., LTD.. The grantee listed for this patent is FUJI MANUFACTURING CO., LTD. Invention is credited to Shozo Ishibashi, Masatoshi Kitagami, Keiji Mase, Yuya Takahashi.
United States Patent |
10,131,036 |
Mase , et al. |
November 20, 2018 |
Method and device for manufacturing elastic abrasive method for
blasting the elastic abrasive including method for recycling the
elastic abrasive and device for blasting the elastic abrasive
including device for recycling the elastic abrasive
Abstract
To obtain a circulation-type blasting device which enables
stable processing for a long period of time even in a case that an
elastic abrasive of which abrasive grains are attached to a surface
of an elastic core are used. A circulation-type blasting device is
provided with a device for recycling an elastic abrasive for
recycling all or a part of elastic abrasive used in a cyclic way,
and the device for recycling the elastic abrasive is provided with
a mixing unit for mixing recovered abrasives recovered from an
abrasive recovery unit and abrasive grains introduced from an
abrasive grain supplying unit in a gas flow by introducing the
abrasive grains and the recovered abrasive in the gas flow to
generate a solid-gas biphase flow, and a combining unit composed of
at least one bent space to which the solid-gas biphase flow is
introduced.
Inventors: |
Mase; Keiji (Tokyo,
JP), Ishibashi; Shozo (Tokyo, JP),
Takahashi; Yuya (Tokyo, JP), Kitagami; Masatoshi
(Tokyo, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
FUJI MANUFACTURING CO., LTD |
Tokyo |
N/A |
JP |
|
|
Assignee: |
FUJI MANUFACTURING CO., LTD.
(Tokyo, JP)
|
Family
ID: |
52740615 |
Appl.
No.: |
14/492,543 |
Filed: |
September 22, 2014 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20150093969 A1 |
Apr 2, 2015 |
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Foreign Application Priority Data
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|
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Sep 30, 2013 [JP] |
|
|
2013-205030 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24C
9/006 (20130101); B24C 11/00 (20130101); Y02P
70/10 (20151101); Y02P 70/179 (20151101) |
Current International
Class: |
B24C
9/00 (20060101); C09K 3/14 (20060101); B24C
11/00 (20060101) |
Field of
Search: |
;51/298 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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S55-98565 |
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Jul 1980 |
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JP |
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09-314468 |
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Dec 1997 |
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JP |
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2001-207160 |
|
Jul 2001 |
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JP |
|
2006-159402 |
|
Jun 2006 |
|
JP |
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2008-264953 |
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Nov 2008 |
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JP |
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2008-8264953 |
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Nov 2008 |
|
JP |
|
2009-125818 |
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Jun 2009 |
|
JP |
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2009-215327 |
|
Sep 2009 |
|
JP |
|
Other References
JP 2008-264953 A--Nov. 2008--English Machine Translation. cited by
examiner .
Corresponding Japanese Application 2013-205030, Japanese Office
action dated Jun. 21, 2017, 9 pages. cited by applicant.
|
Primary Examiner: Carlson; Marc
Attorney, Agent or Firm: Cooper Legal Group LLC
Claims
What is claimed is:
1. A method for recycling elastic abrasives in a circulation-type
blasting in which each elastic abrasive comprising a core made of
an elastic material having adhesiveness at least on a surface of
the core and abrasive grains attached to the surface of the core is
ejected into a blasting chamber, then recovered and recycled
thereby reused, thereby a circulation system of the elastic
abrasives is formed, comprising: a mixing step for mixing new
abrasive grains and recovered elastic abrasives each of which
having its respective core and an exposed part where abrasive
grains have fallen off from its respective surface of its
respective core in a compressed gas flow by introducing then
joining a predetermined amount of the new abrasive grains into the
compressed gas flow to generate a mixed flow, then introducing and
joining a predetermined amount of the recovered elastic abrasives
the mixed flow to generate a solid-gas biphase flow for evenly
attaching the new abrasive grains to each of the exposed part of
the surface of the core without aggregation of the core; and a
combining unit composed of a conduit having a bent space formed
into a curved shape of which radius of curvature is gradually
decreased and curvature is increased as extending from an upstream
side to a downstream side to which the solid-gas biphase flow
including the recovered elastic abrasives each of which has the
core having the surface to which the new abrasive grains are
attached in the mixing unit is introduced then the new abrasive
grains attached to each of the surface of the core of the recovered
elastic abrasive are pressed and combined to each of the surface of
the core of the recovered elastic abrasive to obtain recycled
elastic abrasives.
2. The method for recycling the elastic abrasives according to
claim 1 further comprising an inspection step for measuring an
amount of the abrasive grains attached to the surface of the core
of the elastic abrasive recovered through the combining step,
wherein the amount of the abrasive grains to be joined in the
mixing step is adjusted so that the amount of the abrasive grains
to be measured in the inspection step approximates to a
predetermined target amount of attachment.
3. The method for recycling the elastic abrasives according to
claim 2, wherein the amount of the abrasive grains attached to the
surface of the core in the inspection step is measured by measuring
a repose angle of the recovered elastic abrasive.
4. The method for recycling the elastic abrasives according to
claim 1, wherein the solid-gas biphase flow is generated by
introducing the predetermined amount of the recovered elastic
abrasives into the compressed gas to generate a mixed flow, then
introducing and joining the predetermined amount of new abrasive
grains into the mixed flow of the recovered elastic abrasives and
the compressed gas.
5. A device for recycling elastic abrasives incorporated in a
circulation -type blasting device composed of a blasting chamber
including an abrasive ejecting device for ejecting the elastic
abrasives each of which comprising a core made of an elastic
material having adhesiveness at least on a surface of the core and
abrasive grains attached to the surface of the core and a
circulation system of the elastic abrasives for circulating the
elastic abrasives from the blasting chamber to the abrasive
ejecting device through an abrasive recovery unit, the device for
recycling the elastic abrasives comprising: a mixing unit for
mixing a predetermined amount of new abrasive grains and recovered
elastic abrasives which are recovered from the abrasive recovery
unit and each of which having its respective core and an exposed
part where abrasive grains have fallen off from its respective
surface of its respective core by introducing then joining the new
abrasive grains into the compressed gas to generate a mixed flow,
then introducing and joining a predetermined amount of the elastic
abrasives which are recovered from the abrasive recovery unit in
the mixed flow to generate a solid-gas biphase flow for evenly
attaching the new abrasive grains to each of the exposed part of
the surface of the core without aggregation of the core, and
attaching the new abrasive grains to each of the exposed part of
the surface of the core of the recovered elastic abrasive; and a
combining unit composed of a conduit having a bent space formed
into a curved shape of which radius of curvature is gradually
decreased and curvature is increased as extending from an upstream
side to a downstream side to which the solid-gas biphase flow
including the recovered elastic abrasives each of which has the
core having the surface to which the new abrasive grains are
attached in the mixing unit is introduced then the new abrasive
grains attached to each of the surface of the core of the recovered
elastic abrasive are pressed and combined to each of the surface of
the core of the recovered elastic abrasive to obtain recycled
elastic abrasives.
6. The device for recycling the elastic abrasives according to
claim 5 further comprising: a measuring device for measuring an
amount of the abrasive grains attached to the surface of the core
of the elastic abrasive obtained by the combining unit; an abrasive
grain regulator capable of changing a supplying amount of the
abrasive grains to the mixing unit; and a controller for
controlling the supplying amount of the abrasive grains by the
abrasive grain regulator so that the amount of the abrasive grains
to be measured by the measuring device approximates to a
predetermined target amount of attachment.
7. The device for recycling the elastic abrasives according to
claim 6, wherein the measuring device measures a repose angle of
the elastic abrasive as the amount of the abrasive grains attached
to the surface of the core.
8. The device for recycling the elastic abrasives according to
claim 5 whether the mixing unit comprises: a first body in which an
abrasive grain sucking chamber communicating with an abrasive grain
supplying unit for constantly supplying the predetermined amount of
new abrasive grains is formed; a second body in which a
recovered-abrasive sucking chamber communicating with the abrasive
recovery unit is formed, the second body being coupled to the first
body through an intermediate housing; a first air jetting unit with
its rear end communicated with the compressed air source and its
front end inserted into the abrasive grain sucking chamber of the
first body; and a second air jetting unit with its rear end
directed at the front end of the first air jetting unit and its
front end inserted into the recovered-abrasive sucking chamber,
wherein the compressed gas flow from the compressed gas source is
introduced into the first air jetting unit, the compressed gas is
ejected from the front end of the first air jetting unit to the
rear end of the second air jetting unit, then negative pressure is
created in the abrasive grain sucking chamber by ejection of the
compressed gas flow, the abrasive grains from the abrasive grain
supplying unit is sucked into the abrasive grain sucking chamber,
and joined or introduced in compressed gas flow ejected from the
front end of the first air jetting unit then introduced into the
second air jetting unit, and the mixed flow of the new abrasive
grains and the compressed gas flow introduced into the second air
jetting unit is ejected in the recovered-abrasive sucking chamber
toward the outlet of the mixing unit, thereby the negative pressure
is created in the recovered-abrasive sucking chamber, and the
predetermined amount of the elastic abrasives recovered in the
abrasive recovery unit are introduced into the recovered-abrasive
sucking chamber and joined or introduced in the mixed flow
containing the abrasive grains, then ejected from the mixing
unit.
9. The device for recycling elastic abrasives according to claim 5,
wherein the solid-gas biphase flow is generated by introducing the
predetermined amount of the recovered elastic abrasives into the
compressed gas to generate a mixed flow, then introducing and
joining the predetermined amount of new abrasive grains into the
mixed flow of the recovered elastic abrasives and the compressed
gas.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and a device for
manufacturing an elastic abrasive, a method and device for
blasting, more specifically, relates to a method for manufacturing
an elastic abrasive having a structure that abrasive grains are
attached to a surface of an elastic core and a device for carrying
out the method, and a method and device for circulation-type
blasting structurally including the method or the device for
manufacturing the elastic abrasive as a method or device for
recycling the elastic abrasive.
Note that the "manufacture" of the elastic abrasive in the present
invention includes attachment of the abrasive grains to the surface
of the unused core, as well as "recycle" by (re)attaching the
abrasive grains to the surface of the core of the elastic abrasive
on which the abrasive grains are removed from the surface by use
(including the core on which abrasive grains are remained).
2. Description of the Related Art
Various elastic abrasives having cores which carry abrasive grains
e.g. by kneading the abrasive grains into elastic cores or
attaching the abrasive grains to the surfaces of the elastic cores
have been proposed (Japanese Patent No. 2,957,492, Japanese Patent
Laid-Open No. 2001-207160, Japanese Utility Model Laid-Open No.
S55-98565), and a shock caused by collision with a workpiece is
absorbed due to elasticity of the core by blasting using this
elastic abrasive. As a result, a satin finished surface formed on
the surface of the workpiece caused by general blasting is reduced
while processings such as polishing, removal of an oxide film and
deburring are enabled for the workpiece.
Particularly, in an elastic abrasive using a core suppressing
impact resilience for preventing recoiling in collision, mirror
finishing which was impossible in the conventional blasting can
also be carried out by sliding an ejected elastic abrasive on a
surface of the workpiece, which considerably contributes to widen
uses of the blasting (Japanese Patent Laid-Open No.
2006-159402).
A structure of such an elastic abrasive may include a structure
that abrasive grains are kneaded into a core composed of an elastic
material such as a rubber to make the core to carry the abrasive
grains (see UM '8565), and structures that abrasive grains are
attached to a surface of a core such as a structure that a plant
fiber having adhesiveness in its oil and sugar contents is used as
a core (Pat '7492) or a structure that a gelatin which exerts
adhesiveness and elasticity depending on water content is used as a
core ('7160).
Particularly, for manufacture of the elastic abrasive having the
structure that the abrasive grains are attached to the surface of
the core, the core was introduced into a rotating drum together
with abrasive grains and stirred as it is in a case of a core
exerting self-adhesiveness such as a plant fiber having
adhesiveness in its oil and sugar contents and gelatin as mentioned
above, or through coating of the core with an adhesive or an
agglutinant in a case using a resin such as polyurethane without
self-adhesiveness as a core, so that the abrasive grains are
contacted then firmly and densely attached to the surface of the
core by colliding, rubbing and pressing the core contacted with the
abrasive grains to the inner wall of the drum and other cores by
centrifugation. This method is also used for recycling the elastic
abrasive with surface from which the abrasive grains were fallen
off by use.
In the case that the elastic abrasive including a core which exerts
adhesiveness and elasticity by containing water is used among the
above-mentioned elastic abrasives, in light of change of the
processed state according to the change of the elasticity and
adhesiveness of the core by drying with time, it is also proposed
that, in a circulation-type blasting device which recovers an
abrasive once ejected and re-ejects it, the water content of the
elastic abrasive can be adjusted by providing a liquid supplying
means which sprays water in a circulation system of the elastic
abrasive (Japanese Patent Laid-Open No. 2009-125818).
In the case that blasting is carried out by using the elastic
abrasive having a structure that abrasive grains are attached to a
surface of the core among the elastic abrasives described as
related art, the abrasive grains attached to the surface of the
core of the elastic abrasive are fallen off by impact and friction
in collision, and the amount of the abrasive grains attached to the
surface of the core is decreased as the number of the collision
with the workpiece increases.
Hence, in the case that blasting using an elastic abrasive is
carried out in a circulation-type blasting device, cutting
performance of the elastic abrasive gradually decreases with time
as shown in FIG. 10, and there is a large difference in states of
the surfaces such as gloss and specularity between a processed
state of a workpiece processed by the new elastic abrasive and a
processed state of a workpiece processed by using the elastic
abrasive repeatedly used.
Even if the elastic abrasive is exchanged for new abrasive at
regular intervals in order to prevent the change of the processed
state, the cutting amount is temporarily increased immediately
after the exchange, however the cutting amount is decreased with
time, the cutting amount unstably changes as shown in FIG. 10, and
therefore the workpiece still cannot be processed with a certain
level of quality.
Thereby, in the case that blasting is carried out by using an
elastic abrasive having a structure that abrasive grains are
attached to a surface of the core, it is necessary to use batch
processing by exchanging the elastic abrasive at each time of use
or exchange for a new elastic abrasive in a short period after
recycling several times. Therefore, there is a problem that the
productivity is considerably decreased because the blasting is
interrupted by each exchange.
As presented in '5818, in order to uniform the processed state in
blasting using the elastic abrasive comprising the core having
elasticity and adhesiveness which is changed according to change of
water content, it is proposed to prevent change of the processed
state accompanying dry of the elastic abrasive even in a case of
recycling use of the elastic abrasive by providing a liquid
supplying unit which sprays water into the circulation system of
the abrasive in the circulation-type blasting device. Also in
relation to the abrasive grains fallen off from the surface of the
core, if the elastic abrasive can be similarly recycled in the
circulation system of the abrasive, the blasting can be
continuously carried out without interrupting the processing.
However, the elastic abrasive with the core from which the abrasive
grains are fallen off is recycled by introducing the elastic
abrasive to be recycled into the drum together with the abrasive
grains and stirring as mentioned above then densely and firmly
attaching the abrasive grains not only by attaching new abrasive
grains to the core exposed by which the abrasive grains are fallen
off, but also by pressing and fixing the new abrasive grains to the
surface of the core by giving collision, friction and centrifugal
force generated in stirring. Consequently, it is impossible to
recycle an elastic abrasive simply by spraying water to the elastic
abrasive circulating in the blasting device.
On the other hand, since the above-mentioned drum-shaped
manufacturing device for elastic abrasive is large in size, the
structure of the device is getting larger in a case that this
device is combined with a circulation-type blasting device.
Furthermore, since the recycle of the elastic abrasive in the
drum-shaped manufacturing device is carried out in the batch style,
even if the manufacturing device is combined with the
circulation-type blasting device, the blasting device must be
eventually stopped for recycling the elastic abrasive.
The present invention has been made to solve the problems in the
related art described above, and an object thereof is to provide a
method and a device for manufacturing an elastic abrasive having a
core to which abrasive grains are densely and firmly attached like
the above-mentioned drum-shaped device for manufacturing the
elastic abrasive, while enabling the device to be downsized and to
continuously manufacture the elastic abrasive, thus enabling to
incorporate the process and/or device for recycling the elastic
abrasive in the device for circulation-type blasting or the process
using the device for circulation-type blasting, thereby the
workpiece can be continuously processed for the long time while
maintaining the processed state of the workpiece constant in the
blasting using the elastic abrasive.
SUMMARY OF THE INVENTION
Means for solving the problems are described below with reference
numerals used in the detailed description of the preferred
embodiments. These reference numerals are intended to clarify the
correspondence between the descriptions in the claims and the
descriptions in the detailed description of the preferred
embodiments, and it is needless to say that these reference
numerals should not be used to restrictively interpret the
technical scope of the present invention.
In order to achieve the above described objective, a method and
device for manufacturing an elastic abrasive composed of a core
made of an elastic material and having adhesiveness at least on a
surface of the core and abrasive grains attached to the surface of
the core according to the present invention, comprises:
a mixing unit 11 for carrying out a mixing step for mixing the
abrasive grains and the core in a gas flow by introducing the
abrasive grains and the core together in the gas flow to generate a
solid-gas biphase flow; and
a combining step for combining the abrasive grains with the surface
of the core by introducing the solid-gas biphase flow generated in
the mixing step in a mixing unit 11 in a combining unit 12 having a
conduit with at least one bent space in embodiments (121, 122 or
123) then passing through the bent space (121, 122 or 123) by
propulsive force and/or centrifugal force of the solid-gas biphase
flow thereby pressing the abrasive grains to the surface of the
core.
The method or device may further comprises:
an inspection means 14 for carrying out an inspection step for
measuring an amount of the abrasive grains attached to the surface
of the core of the elastic abrasive obtained by the combining unit
12;
an abrasive grain weighing means 131 capable of changing a
supplying amount of the abrasive grains to the mixing unit 11;
and
a controlling means 15 for adjusting the supplying amount of the
abrasive grains by controlling the abrasive grain weighing means
131 so that the amount of the abrasive grains to be measured in the
inspection step approximates to a predetermined target amount of
attachment.
In such a case, the amount of the abrasive grains attached to the
surface of the core in the inspection step is measured by measuring
a repose angle of the recovered elastic abrasive.
Preferably, the bent space 123 arranged in the combining unit 12 is
formed into a curved shape which is steeply changed (i.e.,
curvature is increased) as extending from an upstream side to a
downstream side.
Furthermore, a method and device for blasting according to the
present invention comprises the above described method or device
for manufacturing the elastic abrasive as a step for recycling the
elastic abrasive or the device for recycling the elastic abrasive
10, and the method and device use a circulation-type blasting
device composed of a blasting chamber 8 in which an abrasive is
ejected, an abrasive recovery unit 20 communicated with a bottom of
the blasting chamber 8 and an abrasive ejecting means 30 for
ejecting the abrasive in the abrasive recovery unit 20 into the
blasting chamber 8 and forming a circulation system of the abrasive
for circulating the abrasive from the blasting chamber 8 through
the abrasive recovery unit 20 to the abrasive ejecting means 30,
and using an elastic abrasive composed of a core made of an elastic
material and having adhesiveness at least on a surface of the core
and abrasive grains attached to the surface of the core as the
abrasive, and comprises
a device for recycling an elastic abrasive 10 for recycling the
elastic abrasive circulating in the circulation system of the
abrasive; and
the device for recycling the elastic abrasive 10 includes:
a mixing unit 11 for carrying out a mixing step for mixing abrasive
grains from an abrasive grain supplying unit 13 and a recovered
abrasive recovered from the abrasive recovery unit 20 in a gas flow
by introducing the recovered abrasive and the abrasive grains
together in the gas flow to generate a solid-gas biphase flow;
and
a combining step for combining the abrasive grains with an exposed
surface of the core of the recovered abrasive by introducing the
solid-gas biphase flow generated in the mixing unit 11 into a
combining unit 12 having a conduit with at least one bent space
(121, 122 or 123) and passing through the bent space (121, 122 or
123) by propulsive force and/or centrifugal force of the solid-gas
biphase flow thereby pressing the abrasive grains to the exposed
surface of the core of the recovered abrasive.
The device for recycling the elastic abrasive 10 may be provided
outside the circulation system of the abrasive, and the elastic
abrasives recovered in the abrasive recovery unit 20 is partially
introduced as the recovered abrasives into the device for recycling
the elastic abrasive 10 to carry out the mixing step and the
combining step, then recycled elastic abrasives obtained through
the combining step are returned to the circulation system of the
abrasive at any position.
Furthermore, the device for recycling the elastic abrasive 10 may
comprise an inspection means 14 for measuring an amount of the
abrasive grains attached to the surface of the core of the recycled
elastic abrasive obtained through the combining step,
an abrasive weighing means 131 capable of changing an amount of the
abrasive grains to be introduced to the mixing unit 11, and
a controlling means 15 for controlling an introduction amount of
the abrasive grains by the abrasive grain weighing means 131 is
provided so that the amount of the attached abrasive grains
measured by the inspection means 14 approximates to a predetermined
target amount of attachment.
In such a case, the amount of the abrasive grains attached to the
surface of the core of the recycled elastic abrasive may be
measured in the inspection step by measuring a repose angle of the
recovered recycled elastic abrasive.
Preferably, the bent space 123 arranged in the combining unit 12 is
formed into a curved shape which is steeply changed (i.e.,
curvature is increased) as extending from an upstream side to a
downstream side.
According to the configuration of the present invention described
above, by means of the method and device for manufacturing the
elastic abrasive of the present invention, the abrasive grains
could be evenly attached to the adhesive core without aggregation
of the core by mixing the abrasive grains and the core with a
mixing unit 11 in which the abrasive grains and the core are
introduced in a gas flow to generate a solid-gas biphase flow, and
the core to which the abrasive grains are attached in such a way
was introduced to a combining unit 12 comprising a conduit having
one or more bent spaces (121, 122 or 123), thereby, during passing
through the bent spaces (121, 122 or 123) of the combining unit 12,
the core to which the abrasive grains are attached e.g. by being
collided with the inner wall of the combining unit 12 and other
cores by propulsive force and/or centrifugal force of the solid-gas
biphase flow, or rotated on the wall in the combining unit 12 while
being pressed to the inner wall of the combining unit 12 to enable
the abrasive grains to densely and firmly attach to the core.
As a result, there could be provided a device for manufacturing an
elastic abrasive considerably downsized compared to a conventional
drum-shaped device for manufacturing elastic abrasive, enables to
continuously manufacture the elastic abrasive in a non-batch style
while obtaining the same elastic abrasive as that manufactured by
the conventional drum-shaped device for manufacturing elastic
abrasive.
As a result, the device for manufacturing the elastic abrasive of
the present invention could be incorporated as a device for
recycling an elastic abrasive 10 in a circulation-type blasting
device to provide a blasting device 1 which enabled continuous
blasting for a long period of time while maintaining a constant
accuracy for processing without exchange of the elastic abrasive by
incorporating such a device for recycling an elastic abrasive 10
into the circulation-type blasting device to recycle the elastic
abrasive circulating in the blasting device.
In a configuration that an inspection means 14 for inspecting an
amount of the abrasive grains attached to the core of the elastic
abrasive (recycled elastic abrasive) obtained by the combining unit
12, an abrasive grain weighing means 131 for adjusting an amount of
the abrasive grains to be introduced to the mixing unit 11, as well
as a controlling means 15 which adjusted the abrasive grain
weighing means 131 so that the amount of the attached abrasive
grains measured in the inspection means 14 was constant were
installed, the amount of the attached abrasive grains to the core
of the obtained elastic abrasive could always be made constant, and
the quality of the obtained elastic abrasive could be uniformed.
Additionally, in the blasting device 1 into which such device for
manufacturing an elastic abrasive was incorporated as the device
for recycling the elastic abrasive 10, unevenness in the processed
state could be prevented even if the blasting was continued for a
long period of time.
In addition, the exposed area of the adhesive surface of the core
is changed depending on the change of the state of the abrasive
grains attached to the core. In the case that the amount of the
attached abrasive grains is small, the elastic abrasives are likely
to be adhered each other, and in the case that the amount of the
attached abrasive grains is increased, the elastic abrasives are
hardly attached to each other.
Thus, such a state of attachment of abrasive grains could be
relatively easily and accurately measured by measuring an angle of
inclination (repose angle) of a side face of a cone formed of the
elastic abrasive (recycled elastic abrasive) piled in a cone
shape.
As the core (recovered abrasive) passing through the bent space
arranged in the combining unit 12 moved from an upstream side to a
downstream side, its propulsive force or movement speed was
decreased, therefore, a centrifugal force acting on the core was
decreased with the approach of downstream side, accordingly the
force for pressing the core to the inner wall of the combining unit
was decreased in the configuration having a bent space 122 curved
in a constant curvature as shown in FIG. 4B. However, as mentioned
above, in the structure that the bent space arranged in the
combining unit 12 was formed into a curved shape which is steeply
changed (i.e., increasing a curvature) as extending from the
upstream side to the downstream side as shown in FIG. 4C, the
decrease of the centrifugal force acting on the core could be
suppressed even if the movement speed is decreased. Consequently,
the abrasive grains could be more preferably attached to the
core.
BRIEF DESCRIPTION OF THE DRAWINGS
The objects and advantages of the invention will become apparent
from the following detailed description of preferred embodiments
thereof provided in connection with the accompanying drawings in
which:
FIG. 1A shows a front view and FIG. 1B shows a side view of the
blasting device of the present invention;
FIG. 2 shows an explanatory drawing of the device for recycling the
elastic abrasive;
FIG. 3 shows a schematic cross-sectional view of the mixing
unit;
FIG. 4 shows an explanatory drawing of the combining unit wherein
FIG. 4A is an example that bent spaces in a linear shape are
provided, FIG. 4B and FIG. 4C are examples that bent spaces in a
curved shape are provided;
FIG. 5 shows a schematic view of the abrasive grain supplying
unit;
FIG. 6 shows a schematic view of the abrasive grain-weighing means
wherein FIG. 6A is a sectional front view and FIG. 6B is a
cross-sectional view taken along the line B-B in FIG. 6A;
FIG. 7 shows a graph showing the change of the cutting amount
relative to the ejection time in Example 1;
FIG. 8 shows a graph showing the change of the cutting amount
relative to the ejection time in Example 2;
FIG. 9 shows a graph showing the changes of the cutting amounts
relative to the ejection times in Comparative Examples (Comparative
Example 1, 2); and
FIG. 10 shows an explanatory drawing showing a relationship between
the ejection time and the cutting amount in conventional blasting
using the elastic abrasive.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Next, the embodiment of the present invention will be described
below with reference to the appended drawings.
In the embodiment to be described below, a configuration that a
device for manufacturing an elastic abrasive according to the
present invention is incorporated as a device for recycling an
elastic abrasive in a circulation-type blasting device will be
described. However the device for manufacturing the elastic
abrasive according to the present invention can be used alone for
manufacturing the elastic abrasive without being incorporated into
the blasting device.
Elastic Abrasive to be Recycled or the Like
In addition, the elastic abrasive to be manufactured or recycled in
the present invention is composed of an elastic core having
adhesiveness at least on its surface and abrasive grains attached
to the surface of the core. As long as the abrasive has this
structure, various materials, sizes, shapes, etc. can be applied,
and the abrasive may also be an abrasive in which the abrasive
grains are attached to the surface of the core composed of a
self-adhesive material like a gelatin and an elastomer, or may be
an elastic abrasive in which the abrasive grains are attached to
the surface of the core to which adhesiveness is given by coating a
surface of a resin of polyurethane etc. with the self-adhesive
material.
Also, for the abrasive grains to be used, various abrasive grains
can be used. However, as an example, diamond, cBN, silicon carbide,
alumina, zircon, high-speed steel, iron-carbon alloy, glass, resin,
copper and its alloy, aluminum and its alloy, etc. can be used, and
one or a combination of a plurality of them may be used.
Furthermore, the grain diameter of the abrasive grain can also be
selected from various grain diameters depending upon applications
of the desired elastic abrasive and can be selected from a range of
0.05 .mu.m to 1 mm in a median diameter (hereinafter referred to as
"D50") as one example, and its shape can also be selected from
various shapes such as amorphous shapes, polygons, spherical shapes
and cylindrical shapes.
Basic Structure of the Blasting Device
Examples of the structure of the blasting device according to the
present invention provided with a device for recycling an elastic
abrasive 10 is shown in FIGS. 1A, 1B.
A blasting device 1 shown in FIG. 1 is a circulation-type blasting
device provided with a blasting chamber 8 formed in a cabinet 7 in
which ejection of the abrasive is carried out, an abrasive recovery
unit 20 for recovering the abrasive, which is a recovering hopper
communicating with a bottom of the blasting chamber 8, and an
abrasive ejecting means 30 which ejects the abrasive in the
abrasive recovery unit 20 into the blasting chamber 8, wherein a
circulation-type system of the abrasive from the blasting chamber 8
through the abrasive recovery unit 20 and an abrasive supplying
tube 41 to the abrasive ejecting means 30 is formed, and the
abrasive ejected from the abrasive ejecting means 30 is composed so
as to circulate this system and to be re-ejected by the abrasive
ejecting means 30.
Although, in the illustrated embodiment, as the abrasive ejecting
means 30 which ejects the abrasive in the blasting chamber 8, there
is provided a blast gun which ejects the abrasive on a compressed
air from a compressed air source (not shown), the ejection of the
abrasive is not limited to such an air type, and known various type
of abrasive-ejecting means other than acceleration by compressed
air can also be adopted, as long as they are dry types capable of
ejecting or projecting the abrasive such as a hitting type to hit
an abrasive by colliding the abrasive against a rotating impeller
and a centrifugation type to eject the abrasive by centrifugal
force (collectively referred as "ejection" in the present
invention).
A bottom of the blasting chamber 8 for carrying out ejection of the
abrasive by the abrasive ejecting means 30 is formed into
reverse-pyramid shape so as to have a hopper-shape, thus the
abrasive ejected in the blasting chamber 8 is fallen into the
hopper-shaped abrasive recovery unit 20.
A baffle plate for classifying the elastic abrasive and dusts is
arranged in the blasting chamber 8, the elastic abrasive is
recovered in the abrasive recovery unit 20 by the classification
through the baffle plate, and the dusts are introduced into a dust
collector 26 provided at the back of a cabinet 7 by an exhauster
(blower) 25 and collected.
A bottom of the abrasive recovery unit 20 in which the elastic
abrasive is recovered is communicated with the abrasive supplying
tube 41, and the abrasive supplying tube 41 is communicated with
the abrasive ejecting means 30 which is a suction-type blast gun in
the illustrated example.
In the present embodiment, the configuration that the elastic
abrasive and dusts were classified by the baffle plate was
described. However instead of this configuration, the elastic
abrasive and dusts may be classified e.g. by employing a
cyclone-type abrasive tank as the abrasive recovery unit 20.
Compressed air from the compressed air source (not shown) is
introduced into the blast gun 30. By introducing compressed air
from the compressed air source into the blast gun 30, the abrasive
in the abrasive recovery unit 20 is sucked through the abrasive
supplying tube 41 by a negative pressure caused in the blast gun 30
thereby the abrasive can be ejected into the blasting chamber 8
together with compressed air.
Thus, the illustrated circulation-type blasting device 1 is
configured so that the abrasive can be circularly used to continue
the blasting for a long period of time, because the circulation
system of the abrasive in which the abrasive ejected by the
abrasive ejecting means 30 is re-introduced into the abrasive
ejecting means 30 through the blasting chamber 8 and the abrasive
recovery unit 20 then ejected is formed.
Device for Recycling Elastic Abrasive
In the circulation-type blasting device 1 configured as described
above, the blasting can be continuously carried out for a long
period of time by using the abrasive in a circulative way. However
in a case that the elastic abrasive having a structure that the
abrasive grains are attached to the surface of the elastic core is
used as an abrasive, the abrasive grains attached to the surface of
the core fall off by collision with the workpiece, accordingly a
cutting ability of the abrasive is gradually lowered by repeatedly
using the abrasive in the circulative way, hence even if the
processing is carried out while maintaining other processing
conditions such as ejection pressure and ejection speed to be
constant, the processed state of the workpiece is changed.
Thus, in the blasting device 1 of the present invention, by
providing the device for recycling the elastic abrasive 10 for
recycling the elastic abrasive circulating in the circulation
system of the abrasive mentioned above, the blasting can be
continued for a long period of time without changing the processed
state even if time passes.
The device for recycling the elastic abrasive is indicated by
reference numeral 10 in FIG. 2. The device for recycling the
elastic abrasive 10 comprises at least a mixing unit 11 for mixing
the recovered abrasive with the abrasive grains and a combining
unit 12 for pressing and combining the abrasive grains to the
surface of the core of the recovered abrasive in which the exposed
part of the core is attached to the abrasive grains by mixing with
the mixing unit 11. In the illustrated embodiment, the mixing unit
11 and the combining unit 12 are provided as a flow channel apart
from the circulation system of the abrasive.
Furthermore, in the illustrated embodiment, an abrasive grain
supplying unit 13 which introduces the abrasive grains into the
mixing unit 11 includes an abrasive grain weighing means 131 (see
FIG. 5, 6) which can change an amount of the abrasive grains to be
introduced. In addition, an inspection means 14 is provided for
measuring an amount of the abrasive grains attached to the surface
of the core of the recycled elastic abrasive recycled by being
combined through the combining unit 12. Furthermore, a controlling
means 15 is provided for controlling the abrasive grain weighing
means 131 to change the amount of the abrasive grains to be
introduced by receiving feedback of a result measured by the
inspection unit 14 so that the measured amount of the attached
abrasive grains approximates to a predetermined target amount of
attachment.
Mixing Unit
In the mixing unit 11 mentioned above, the recovered abrasive to be
recycled and the abrasive grains to be attached to the surface of
the core of the recovered abrasive are joined or introduced in a
gas flow to generate a solid-gas biphase flow, thereby the
recovered abrasive and the abrasive grains are mixed in the gas
flow, and new abrasive grains are attached to a part of the core
exposed by falling off the abrasive grains in the surface of the
recovered abrasive.
As shown in FIG. 3, in this mixing unit 11, a first body 111 in
which an abrasive grain sucking chamber 112 is formed is coupled to
a second body 113 in which a recovered-abrasive sucking chamber 114
is formed through an intermediate housing 115. Furthermore, the
mixing unit 11 is provided with a first air jetting unit 116 and a
second air jetting unit 117, and a rear end of the first air
jetting unit 116 is communicated with the compressed air source
(not shown) and a front end of the first air jetting unit 116 is
inserted into the abrasive grain sucking chamber 112 of the first
body 111, moreover, a rear end of the second air jetting unit 117
is directed at the front end of the first air jetting unit 116 and
an front end the second air jetting unit 117 is inserted into the
recovered-abrasive sucking chamber 114.
In addition, an inlet 112a of the abrasive grain sucking chamber
112 is communicated with the abrasive grain supplying unit 13
through an abrasive grain supplying tube 42, and an inlet 114a of
the recovered-abrasive sucking chamber 114 is communicated with a
bottom of the abrasive recovery unit 20 through a recovered
abrasive supplying tube 43.
In the mixing unit 11 configured as mentioned above, compressed air
from the compressed air source is introduced into the first air
jetting unit 116, the air is ejected from the front end of the
first air jetting unit 116 to the rear end of the second air
jetting unit 117, then negative pressure is created in the abrasive
grain sucking chamber 112 by ejection of the compressed air, the
abrasive grains from the abrasive grain supplying unit 13 is sucked
into the abrasive grain sucking chamber 112, and joined or
introduced in compressed air ejected from the front end of the
first air jetting unit 116 then introduced into the second air
jetting unit 117.
The mixed flow of the abrasive grains and a gas flow introduced
into the second air jetting unit 117 is ejected in the
recovered-abrasive sucking chamber 114 toward the outlet 118 of the
mixing unit 11, thereby the negative pressure is created in the
recovered-abrasive sucking chamber 114, and the elastic abrasives
recovered in the abrasive recovery unit 20 are partially introduced
into the recovered-abrasive sucking chamber 114 as a recovered
abrasive to be recycled and joined or introduced in the gas flow
containing the abrasive grains, then ejected from the mixing unit
11.
Thus, the abrasive grains and the recovered abrasive are joined or
introduced in a gas flow to generate a solid-gas biphase flow,
thereby the abrasive grains and the recovered abrasive can be mixed
without aggregation or the like in this solid-gas biphase flow, and
new abrasive grains are attached to the surface of the core exposed
by falling off the abrasive grains in the recovered abrasive.
As the recovered abrasive, an amount (g/min.) of the elastic
abrasive to be introduced in the mixing unit 11 from the abrasive
recovery unit 20 per a predetermined time is adjusted to preferably
5-50%, more preferably 10-30% of the amount (g/min.) of the
abrasive to be ejected in the blasting chamber per a predetermined
time.
In addition, an amount of the abrasive grains to be introduced to
the mixing unit 11 is adjusted to preferably 3.0% or less, more
preferably 1.0% or less of the amount of the recovered abrasive to
be introduced.
In the case that more than 3.0% of abrasive grains are introduced,
the abrasive grains more than the amount for covering the entire
surface of the recovered abrasive are introduced, therefore a lot
of free abrasive grains which cannot be attached to the surface of
the recovered abrasive are generated, these free abrasive grains
and the elastic abrasive are ejected to the workpiece, resulting in
deterioration of the processed state such as formation of a satin
finished surface on the surface of the workpiece, then such free
abrasive grains are recovered in the dust collector 26 by winnowing
in the abrasive recovery unit 20 for discard, thereby the cost of
the blasting is increased, and particularly in the case that
valuable abrasive grains such as diamond, silicon carbide and cBN
are used, economic burden is further increased.
In the illustrated examples, the space in the first body 111 was
configured as the abrasive grain sucking chamber 112, and the space
in the second body 113 was configured as the recovered-abrasive
sucking chamber 114, however on the contrary, the space in the
first body 111 may be communicated with the abrasive recovery unit
20 to form a sucking chamber for the recovered abrasive, and the
space in the second body 113 may be communicated with the abrasive
grain supplying unit 13 to form a sucking chamber for the abrasive
grains, and as long as the gas flow containing the abrasive grains
and the gas flow containing the recovered abrasive are joined and
mixed, and the abrasive grains can be attached to the surface of
the recovered abrasive, various changes of the configurations are
possible without being limited to the illustrated
configurations.
Combining Unit
By passing through the mixing unit 11, new abrasive grains are
attached to the surface of the core of the recovered abrasive
exposed due to falling off of the abrasive grains with adhesive
force of the core. However, the abrasive grains are attached only
by the adhesive force of the core, accordingly, the state of
attachment between the core and the abrasive grains is still
insufficient.
Thus, the recovered abrasive in this state cannot be reused as an
elastic abrasive just as it is. In order to render the abrasive
tolerable to reuse, the abrasive grains should be firmly combined
with the core through adhesion, embedding or the like by pressing
the abrasive grains toward the core of the recovered abrasive.
In order to combine the core with the abrasive grains as such, the
solid-gas biphase flow generated by the mixing unit 11 is then
introduced into a combining unit 12 composed of a conduit having at
least one or more bent spaces 121, 122 and 123, and by being passed
through the bent spaces 121, 122 and 123, the abrasive grains are
pressed toward the surface of the core of the recovered abrasive by
propulsive force and/or centrifugal force of the solid-gas biphase
flow.
For such a bent space, as shown in FIG. 4A as an example, a part of
the combining unit 12 formed by e.g. a SUS pipe or the like may be
bent to a right angle to form a bent space 121 so that the
recovered abrasive going straight in the combining unit 12 collides
with an inner wall of the combining unit 12 at the bent space 121
to press the abrasive grains against the core.
In the case that the bent space is formed by bending the combining
unit 12 linearly in such a way, the bending angle is not limited to
the right angle as illustrated in the drawing, and it may be bent
at an angle of more than or less than right angle. In addition,
although the illustrated example shows a case that right-angled
bent portions 121 and 121 are given at two portions to form a
square C-shape, the combining unit 12 is not limited to this
example, and may have only one or plural bent spaces.
Furthermore, the bent space may be curved as shown in FIG. 4B or
FIG. 4C, and in a case that the bent space 122 or 123 in a curved
shape is provided in such a manner, the recovered abrasive passing
through the bent spaces 122 and 123 e.g. rotates while being
pressed to an outer periphery side of the inner wall of the
combining unit 12 by centrifugal force, so that the abrasive grains
are firmly pressed to the core by propulsive force and/or
centrifugal force of the solid-gas biphase flow.
In addition, in a case that such the curved bent space is provided,
it may be sequentially formed into a round shape or a spiral
shape.
Moreover, in a case that the bent space with the curved shape is
provided, preferably, the curved shape of the bent space is steeply
changed (i.e., curvature is increased) as extending from an
upstream side to a downstream side as shown in FIG. 4C.
Since the recovered abrasive passing through the bent space
collides with or contact the inner wall of the combining unit 12
thereby its movement speed is gradually lowered as it moves to the
downstream side, the centrifugal force acting on the recovered
abrasive is also gradually lowered.
However, since the centrifugal force acting on objects moving in a
rotational orbit changes in proportion to a product of a distance
from the central axis of the rotation (radius) and squares of the
angular velocity, the decrease of the centrifugal force added to
the recovered abrasive can be suppressed to enable long-time
pressing of the abrasive grains to the core by increasing the
change of the curve (curvature) as extending to downstream side
according to decrease of the movement speed of the recovered
abrasive decreasing as approaching to the downstream side, for
example by increasing the angular velocity of the recovered
abrasive by forming a spiral shape.
In order to obtain a pressing force required for combining the
abrasive grains to the core in any structures, in the case that a
linear bent space is formed, the number of the spaces to be formed
is adjusted, and, in the case that the curved bent space is formed,
the total length (the number of the spiral) of the bent spaces and
the like are adjusted.
In such a way, the abrasive grains are pressed to the core of the
recovered abrasive while passing through the bent space of the
combining unit 12 to obtain a recycled elastic abrasive which were
recycled by densely and firmly attaching the abrasive grains to the
core of the recovered abrasive from which the abrasive grains were
fallen off.
Consequently, the recycled elastic abrasive obtained in such a way
is brought back into the circulation system of the elastic abrasive
in any position, thereby 10-50% of the elastic abrasive circulating
the circulation system is continuously or constantly
(intermittently) recycled. Therefore the elastic abrasive
circulating in the circulation system can always be maintained in a
certain state to constantly maintain the processed state even in a
case of long-time continuous ejection of the elastic abrasive.
Abrasive Grain Supplying Unit
As a configuration of an abrasive grain supplying unit 13 which
introduces the abrasive grains to the mixing unit 11, any
configuration may be used as long as it can constantly supply the
abrasive grains to the mixing unit 11 at a previously set
introduction amount. For example, the abrasive grain supplying unit
13 having a relatively simple structure that a bottom of a hopper
storing the abrasive grains is provided with a predetermined-size
hole or slit, and the abrasive grains passing through the hole or
slit are sent to the mixing unit 11, or the like, may be
provided.
For smoothly supplying the abrasive grains, the hopper storing the
abrasive grains is preferably oscillated, and particularly in the
case that abrasive grains having a grain size of smaller than #3000
(D50: 11 .mu.m) are used, the abrasive grains cannot be transferred
as they are due to strong cohesive force, thus ultrasonic vibration
must be given.
In the present embodiment, the abrasive grain supplying unit 13
includes an abrasive grain weighing means 131 shown in FIGS. 5 and
6 in order to accurately weigh and supply even such fine abrasive
grains, particularly abrasive grains of #6000 (D50: 2 .mu.m) or
smaller with strong cohesive force.
The abrasive grain supplying unit 13 provided with the abrasive
grain weighing means 131 is configured so that a screen 133 made of
a punching metal or a mesh or the like with a large number of small
holes of 0.1-2 mm is arranged below an inverted truncated cone
shaped hopper 132 to allow the abrasive grains introduced into the
hopper 132 to fall on the screen 133. The abrasive grain supplying
unit 13 is also configured so that a rotation axis 134a of a
stirring motor 134 located above the hopper 132 is provided with a
stirring blade 135 rotating in the hopper 132 and a scraper 136
rotating on the screen 133 to allow them to rotate with rotation of
the stirring motor 134.
The scraper 136 has a blade 137 brought into slidable contact with
the surface of the screen 133 as the rotation of the scraper 136,
and is configured so that the abrasive grains can fall from small
holes formed in the screen 133 by the blade 137.
Accordingly, by rotating the stirring motor 134 in a state that the
abrasive grains are delivered in the hopper 132, the abrasive
grains in the hopper 132 are stirred by the stirring blade 135 and
fallen on the screen 133.
The abrasive grains transferred into the small holes of the screen
133 by the blade 137 through the rotation of the scraper 136 pass
through the small holes of the screen 133 and fall downward a small
amount at a time.
Hence, the abrasive grain supplying unit 13 provided with the
abrasive grain weighing means 131 with the above mentioned
structure is configured so that the supplying amount of the
abrasive grains can be increased by accelerating the rotational
speed of the stirring motor 134, conversely, the supplying amount
of the abrasive grains can be decreased by lowering the rotational
speed of the stirring motor 134, thus the supplying amount of the
abrasive grains can be changed by controlling the rotational speed
of the stirring motor 134.
In such a way, an abrasive grain receiving unit 130 into which the
abrasive grains passing through the screen 133 fallen is
communicated with the abrasive grain sucking chamber 112 provided
in the mixing unit 11 through the abrasive grain supplying tube 42
to introduce compressed air to the first air jetting unit 116 in
the mixing unit 11. After the negative pressure is created in the
abrasive grain sucking chamber 112, the abrasive grains are
introduced into the mixing unit 11 together with outside air sucked
from an outside air inlet 130a of the abrasive grain receiving unit
130.
Inspection Means and Controlling Means (Feedback Control)
Thus, the blasting device 1 of the present invention in which the
abrasive grain supplying unit 13 is provided with the abrasive
grain weighing means 131 capable of changing the introduction
amount of the abrasive grains may be configured so that an
inspection means 14 which measures the amount of the abrasive
grains attached to the core of the recycled elastic abrasive
obtained by the combining unit 12 is provided to adjust the amount
of the abrasive grains to be introduced to the mixing unit 11
according to a feedback of inspection results obtained by the
inspection means 14.
The attached amount of the abrasive grains can be measured as a
ratio of a pixel number in areas attaching the abrasive grains and
a pixel number in areas without the abrasive grains or the like
e.g. on the basis of images obtained by photographing the surfaces
of the recycled elastic abrasive particles picked up as samples
from the obtained recycled elastic abrasive. However in the present
embodiment, the amount of the attached abrasive grains is measured
by a repose angle which is a piled angle of the recycled elastic
abrasives piled in a cone shape.
That is, as the exposed area of an adhesive surface of the core
becomes wide by changing the amount of the attached abrasive
grains, the obtained recycled elastic abrasives tend to be adhered
and aggregated each other. Meanwhile, as the exposed area of the
adhesive surface of the core becomes small, the recycled elastic
abrasives become hard to be aggregated each other. As a result, in
the case that the abrasive grains are insufficiently attached to
the core, accordingly the core is exposed, the repose angle is
large. Therefore, a state of attachment of the abrasive grains to
the surface of the core can be measured by measuring the repose
angle of the recycled elastic abrasive.
As the inspection means 14 for measuring the repose angle, various
sensors, CCD cameras, etc. can be used as one example. For example,
the recycled elastic abrasives are piled on a circular plate
disposed at a position which is hardly affected from the
environment until the recycled elastic abrasives are spilled out of
the circular plate, and the repose angle is measured on the basis
of the images obtained by photographing the repose angle of the
pile of the recycled elastic abrasives and the piled height of the
recycled elastic abrasives.
In the illustrated embodiment, an inspection chamber 50
communicated with the blasting chamber 8 is provided, and the
recycled elastic abrasive are fallen off and piled on an inspection
plate 51 provided in the inspection chamber 50, then the recycled
elastic abrasives spilled out from the inspection plate 51 are
fallen into the blasting chamber 8 to return the recycled elastic
abrasive to the circulation system of the abrasive, thereby the
inspection step by the inspection means 14 can be carried out in a
sequence of actions.
The repose angle of the recycled elastic abrasive measured by the
inspection means 14 in such a way is transmitted to the controlling
means 15.
The controlling means 15 is e.g. a microcontroller which controls a
rotational speed of the stirring motor 134 of the abrasive grain
supplying unit 13 on the basis of the repose angle received from
the inspection means 14. On the basis of a correspondence
relationship between the previously memorized repose angle and the
rotational speed of the stirring motor 134, in the case that the
measured repose angle is larger than the objective repose angle,
the rotational speed of the stirring motor 134 is accelerated to
increase the supplying amount of the abrasive grains in order that
the measured repose angle is approximated to the objective repose
angle for obtaining a recycle elastic abrasive with constant
quality.
Modifications
The above-mentioned blasting device 1 of the present invention as
described above has a structure that the device for recycling the
elastic abrasive 10 is provided outside the circulation system of
the abrasive provided in the blasting device 1 and the elastic
abrasives recovered in the abrasive recovery unit 20 are partially
recycled. However, for example, the blasting device 1 may be
configured so that the above described mixing unit 11 and the
combining unit 12 are provided in a flow channel from the abrasive
recovery unit 20 to the abrasive ejecting means 30, and a total
amount of the elastic abrasives recovered in the circulation system
of the abrasive is subjected to the recycling step.
In the above descriptions, as one example, the device for recycling
the elastic abrasive 10 is provided as one component of the
blasting device 1. However, the above-described device for
recycling the elastic abrasive 10 may be separated from the
blasting device 1 and used alone as a device for manufacturing the
elastic abrasive.
In this case, the recovered abrasive described as a subject to be
recycled in the device for recycling the elastic abrasive 10 in the
above embodiment should be replaced by an unused or used core then
used.
EXAMPLES
Hereinafter, the results of a performance verification test for the
blasting device of the present invention equipped with the device
for recycling the elastic abrasive will be described.
Purpose of the Test
The test was carried out to confirm that a deterioration of the
cutting performance can be prevented and the cutting performance
can be stabilized for a long time by carrying our blasting using
the blasting device of the present invention provided with the
device for recycling the elastic abrasive.
Test Method
As elastic abrasives, abrasives ("Sirius Z" manufactured by Fuji
Manufacturing CO., LTD.) with self-adhesive elastomer cores
(average long diameter is 0.3-1.0 mm) to which diamond abrasive
grains #10000 (D50: 0.6 .mu.m) in the amount of 30% with respect to
the weight of the core were attached were used. For the used
abrasives, the abrasives used for 15 hours was used in Example 1,
and the abrasive used for 10 hours was used in Example 2.
As the blasting device (Examples 1, 2) of the present invention, a
commercial air-type blasting device ("SFFSRZ-2", "LDQSR-4", both
were manufactured by Fuji Manufacturing CO., LTD.) as a basis of
the device provided with the device for recycling the elastic
abrasive described with reference to FIGS. 1 and 2 was used to
carry out blasting for test pieces (however, feedback control was
not carried out), and the change of the cutting amount relative to
the processing time was measured.
As comparative examples (Comparative Examples 1, 2), a commercial
blasting device without the device for recycling the elastic
abrasive (the same as the blasting device used as the basis of the
blasting device in Examples 1 and 2) is used to carry out blasting
for test pieces, and the change of the cutting amount relative to
the processing time was measured. In both Comparative Examples, the
elastic abrasive began to be used from an unused state.
The processing conditions in each Example and Comparative Example
are as shown below.
TABLE-US-00001 TABLE 1 Processing conditions in Example 1 and
Comparative Example 1 Comparative Example 1 Example 1 Device for
use SFFSRZ-2 SFFSRZ-2 (with recycling (without recycling device)
device) Amount of the elastic abrasive 1000 g 1000 g (Amount of the
abrasive delivered in the device) Blasting Blast gun Suction type
Suction type condition Nozzle diameter: Nozzle diameter: 9 mm 9 mm
Ejection pressure 0.3 MPa 0.3 MPa Ejection amount 1800 g/min 1800
g/min Distance between 20 mm 20 mm the gun and the test piece
Ejection angle 20.degree. 20.degree. Test piece SUS304 SUS304 (90
.times. 90 .times. 2 mm) (90 .times. 90 .times. 2 mm) Recycle
Pressure intro- 0.3 MPa -- conditions duced to the mixing unit
Recycled Amount 185 g/min -- Supplying amount 0.015 g/min -- of the
abrasive grains
TABLE-US-00002 TABLE 2 Processing conditions in Example 2 and
Comparative Example 2 Comparative Example 2 Example 2 Device for
use LDQSR-4 LDQSR-4 (with recycling (without recycling device)
device) Amount of the elastic abrasive 3000 g 3000 g (Amount of the
abrasive delivered in the device) Blasting Blast gun Direct
pressure Direct pressure condition type Nozzle type Nozzle
diameter: 10 mm diameter: 10 mm Ejection pressure 0.04 MPa 0.04 MPa
Ejection amount 5000 g/min 5000 g/min Distance between the 20 mm 20
mm gun and the test piece Ejection angle 20.degree. 20.degree. Test
piece SUS304 SUS304 (90 .times. 90 .times. 2 mm) (90 .times. 90
.times. 2 mm) Recycle Pressure introduced 0.3 MPa -- conditions to
the mixing unit Amount of recycle 500 g/min -- Supplying amount of
0.075 g/min -- the abrasive grains
Test Results
The relationship between the ejection time and the change of the
cutting amount obtained from the results of the blasting test is
shown in FIGS. 7 to 9. Note that FIGS. 7, 8 and 9 are test results
of Example 1, Example 2 and Comparative Examples (Comparative
Examples 1, 2) respectively.
As is clear from FIGS. 7 to 9, it was confirmed that the processing
could be carried out at a constant cutting amount for a long time
from the start of ejection to the completion of experiment (320
hours in Example 1, and 200 hours in Example 2) in the blasting
using the blasting device of the present invention provided with
the device for recycling the elastic abrasive (see FIGS. 7, 8).
In addition, the state of the elastic abrasive was observed after
the experiment was terminated. According to the observation,
abrasive grains were densely attached to the surface of the core in
the elastic abrasive used in the blasting device of the present
invention, and a definite difference from the elastic abrasive at
the time of the start of use could not be confirmed.
From the above results, it could be confirmed that the elastic
abrasive was preferably recycled by the device for recycling the
elastic abrasive in the blasting device of the present
invention.
On the other hand, in the blasting of Comparative Example 1 using
an existing blasting device without the device for recycling the
elastic abrasive, the cutting amount was considerably decreased in
several hours after the start of processing, the cutting amount was
decreased to more than half of the initial amount by use of 20
hours, and further continued to decrease to about one third by use
of about 50 hours (see FIG. 9).
In Comparative Example 1, an adhesive substance on the core was
adhered to the SUS plate as a test piece, the fluidity of the
elastic abrasive became poor, and the elastic abrasives began to
accumulate on the hopper portion in the processing chamber. Thereby
the processing was terminated.
The elastic abrasive after use of 50 hours was taken out of the
blasting device and its state was confirmed by an optical
microscope. As a result, the abrasive grains were fallen off from
the surface of the core, the core was partially exposed, the core
was worn out by being adhered to the surface of the test piece or
the like, thus reuse was impossible.
Also in Comparative Example 2, the cutting amount was decreased
with time like the case in Comparative Example 1, and decreased to
half by use of 8 hours. The cutting amount was decreased to one
third in 30 hours.
In processing of 70 hours, the adhesive substance of the core was
adhered to the surface of the workpiece, thus uniformly processed
surface could not be obtained.
After the elastic abrasive was used for 70 hours and taken out of
the blast chamber for observing the surface of the abrasive. By an
optical microscope observation, it was confirmed that the abrasive
grains were fallen off from the surface of the core and the core
was partially exposed like the case in Comparative Example 1, thus
reuse was impossible.
Thus the broadest claims that follow are not directed to a machine
that is configure in a specific way. Instead, said broadest claims
are intended to protect the heart or essence of this breakthrough
invention. This invention is clearly new and useful. Moreover, it
was not obvious to those of ordinary skill in the art at the time
it was made, in view of the related art when considered as a
whole.
Moreover, in view of the revolutionary nature of this invention, it
is clearly a pioneering invention. As such, the claims that follow
are entitled to very broad interpretation so as to protect the
heart of this invention, as a matter of law.
It will thus be seen that the objects set forth above, and those
made apparent from the foregoing description, are efficiently
attained and since certain changes may be made in the above
construction without departing from the scope of the invention, it
is intended that all matters contained in the foregoing description
or shown in the accompanying drawings shall be interpreted as
illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended
to cover all of the generic and specific features of the invention
herein described, and all statements of the scope of the invention
which, as a matter of language, might be said to fall
therebetween.
Now that the invention has been described;
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